﻿28 



ACANTTTODII. 



Genus CLIMATIUS, Agassiz. 



[Poiss. Foss. V. G. R. 1845, p. 119.] 



Syn. Br achy acanthus, Sir P. Egerton, Rep. Brit. Assoc. 1859 (1860), 

 Trans. Sect. p. 116. 

 Euthacanthus, J. Powrie, Quart. Jonrn. Geol. Soc. vol. xx. 1864, 

 p. 425. 



Body fusiform, laterally compressed. Teeth minute or absent. 

 Fin-spines extremely robust, marked with coarse longitudinal 

 ridges, sometimes with posterior denticles; first dorsal spine not 

 excessively elongated ; several pairs of free spines on the ventral 

 aspect between the paired fins. 



A detached fin-spine only was known to Agassiz, and the precise 

 definition of the genus was first rendered possible by Egerton's 

 discovery of C. scutiger. 



Climatius reticulatus, Agassiz. 



1845. Climatius reticulatus, L. Agassiz, Poiss. Foss. V. G. R. p. 120, 



pi. xxxiii. fig. 26. 

 1861. Climatius reticulatus, Sir P. Egerton, Figs. & Descrips. Brit. 



Organic Remains (Mem. Geol. Surv.), dec. x. p. 68, pi. viii. figs. 



11-13. 

 1864. Climatius reticulatus, J. Powrie, Quart. Journ. Geol. Soc. vol. xx. 



p. 421. 

 1870. Climatius reticulatus, J. Powrie, Trans. Edinb. Geol. Soc. vol. i. 



p. 295, pi. xiii. fig. 10. 



Type. Detached fin-spine. 



The type species, attaining a maximum length of about 0-2. 

 Body elongated, the greatest depth being contained probably more 

 than five times in the total length ; head and branchial apparatus 

 occupying one fourth of the total length. Spines all short and broad, 

 the longitudinal ridges being more or less tuberculated, and the 

 transverse lines of growth at the base usually prominent. Pectoral 

 fin-spines the largest and most elongated, considerably arched, 

 without posterior denticles ; four pairs of very short and broad, 

 small, intermediate, ventral spines, of which the hindermost pair is 

 the largest ; pelvic fin-spines less than half as large as the pectoral. 

 First dorsal spine shorter, broader, and more curved than the second, 

 situated midway between the pectoral and pelvic pairs ; second 

 dorsal spine comparatively straight, slender, and pointed, similar to 

 the anal, and either directly opposed to the latter or immediately in 

 advance of it. Scales relatively large, smooth, or tuberculated. 



Form. § Loc. Lower Old Red Sandstone : Forfarshire. 



